« on: May 17, 2013, 11:14:46 AM »
would(do) you adjust your rate for the same recipe if the volume change were large(2x)?
I don't, and I don't know of anyone who does. I've worked with one mid-size brewery that has fermenter volumes ranging from 2-8 brew lengths, and their pitching rate is constant across all of them (for a given product). Their consistency is also very good, which probably isn't surprising since they have a full-time QA tech managing their yeast strains.
What I *do* adjust in an effort to maintain consistency is fermentation temperature. My very approximate, entirely anecdotal approach is to add about 1-2°C per 10 bbl of fermenter volume. So where I start most 5 gal batches of ale at 18°C, I start 15 bbl at 20°C and 30 bbl at 21°C. Bear in mind that my atmospheric pressure is already ~4 psi lower, so a 15 bbl batch here is like a 5 gal batch at sea level, at least as far as hydrostatic pressure goes.